Some of my Devices are bypassing Pi-hole DNS and going to GoogleDNS at 8.8.8.8 and 8.8.4.4
My router is not capable of forwarding these UDP requests to Pi-hole.
The router could block these request, but what if I don't want to block them and instead just redirect them to Pi-hole.
I found an "elegant" solution would this be easy to implement on my Pi-hole?
8.8.8.8 is an anycast address. You can basically do the exactly same thing Google does for maintaining one of their boxes that serve the 8.8.8.8 traffic.
Assign the IP address 8.8.8.8 as an additional address on the DNS server, and Possibly add a route if necessary directing 8.8.8.8/32 directing the traffic to your that DNS server.
I think not. Since the clients would be sending the DNS traffic directly to 8.8.8.8, none of this DNS traffic will be seen by your Pi-hole, and thus you will have no opportunity to redirect anything using either Pi-hole or the Pi-hole host device.
Get a router with OpenWrt. It can capture every port access and redirect it to a specified IP address. The client doesn't see this redirection and thinks, that the answer comes from the original IP.
I see the device uses an Allwinner H3 together with a Realtek RTL8211E for the GBit interface (WAN, coupled via H3's RGMII). This combination should be able to get something like up to 600 MBit/s throughput.
The LAN side is done by a dedicated Realtek RTL8152B coupled via USB2.0 (connected to H3's USB-D*1). As the H3 offers three real USB PHYs, there should no issues with Ethernet speed when multiple USB devices are present (this is worth mentioning as the early Raspberry Pis did have this problem). This indeed makes the R1 an interesting approach for a DIY router.
WiFi is done by an AP6212 connected over SDIO which seems a questionable approach. However, this chipset only supports (at most) 72 MBit/s on 2.4 GHz (no 5 GHz support at all) and this may be achievable over SDIO if everything is done properly. But you probably want to do WiFi with a real WiFi AP on the LAN side so this is not of too much interest here.
Do you have any measurements concerning the possible throughout?
I used a R2S as intermediate router as well and it worked fine for a long time. I replaced it by a D-Link router running OpenWRT in between because I wanted proper WiFi from the same box.